Doctrine of merger :-
“22.The doctrine of merger is based on the principles of propriety in the hierarchy of justice delivery system. The doctrine of merger does not make a distinction between an order of reversal, modification or an order of confirmation passed by the appellate authority. The said doctrine postulates that there cannot be more than one operative decree governing the same subject matter at a given point of time.
23. It is trite that when an Appellate Court passes a decree, the decree of the trial court merges with the decree of the Appellate Court and even if and subject to any modification that may be made in the appellate decree, the decree of the Appellate Court supersedes the decree of the trial court. In other words, merger of a decree takes place irrespective of the fact as to whether the Appellate Court affirms, modifies or reverses the decree passed by the trial court.”
Chandi Prasad v. Jagdish Prasad” (2004) 8 SCC 724